When a few others came up with the CoroCub I tuned right in. Thanks for those designs. I have had two Balsa Kit Sig J3-Cubs and loved them. I decided to build one and used the Sig plans as a starting point. It is a little smaller (71 inch wing span) and will fit better in my compact car. The Sig J3-Cub has a cabin are that is very weak in my opinion. I clarify this by stating that I believe a model should come out of a cartwheel in good condition. My planes tend to be heavy. Attached are 5 photos of the fuselage. All Coroplast is 4MM. I'm using 1/16 inch plywood inside the cabin area, reinforced with an additional layer of 1/16 ply at the top and the bottom of the sides. The firewall mounting is exceptionally strong as shown in the photos. The firewall is 7/16 POLY that sandwiches the 4MM Coro against another 7/16 POLY frame that has 7/16 posts for added screw attachments thru the sides and the 1/16 plywood. It is solid and a bit heavy. I hope to add a little more area to the wing to compensate and will use an OS 46FX engine. I would like to read more flying reports on the CoroCubs that are flying.

The above is about my 5th try at up loading the 5 photos. I keep getting an error message. Finally, a few minutes ago I just up loaded the first photo. Here is the second photo. I will follow with individual messages for each of the remaining three photos for a total of five photos.

I was just automatically rejected because I am posting too many messages in a short time. I'm sorry about that. I'm not trying to circumvent anything. Just trying to post five fotos. This time I will try to post the remaining three photos at one time. Could not post all three, so here goes just #3

No joke...great firewall. As far as how these fly...and their toughness. Cartwheeled mine a couple of times in about 20mph winds cause I tried to take off a bit too early and mine cartwheeled beautifully...lol. I know the design seems weak (the middle of the fuse mainly) but its tough as nails. Probably because it flexes so well under stress. Good luck...you'll love how it flies.

Hi Screaming Injun. Do you have wing struts on your's? Are they needed? If you don'r use them, describe the wing spar you are using from a strength point of view. I still have the wing struts from my two crashed basa Sig J-3 Cubs. I'm planing on recycling them on the CoroCub. My main interest is to prevent having wing tip washout. I feel that is what causes snap rolling on a poor takeoff or landing with the J-3 Cub.

No villa....no wing struts. Wing itself is ofcourse as stiff as a 2x4 but i noticed no bending or swaying of the wing in any way. Funny story though on how tough this design is. Few flights back I was too busy yapping at my friend and didn't realize I had hardly even tightend the two plastic bolts that hold the wing down. I flew the plane like it was my last day on earth, landed it, started to disassemble it to load it into my truck, and with only about 5 turns pulled out the bolts. I actually could lift the wing up with about a 1/4 inch gap from the plane. Was shocked and thankful. Wing never fluttered or anything else. So I wouldn't worry about struts too much.

Well...pretty much just your conventional yard stick spar wing...cept for the dow rods on the inside. Mine is the full 82inch wing. I just followed the instructions exactly as shown. The doubled up yard sticks prolly helped alot. I also didn't see a reason to cut out the windows and just used black trim stickers instead. I just couldn't see cutting out the area that supported the wing that much...but I'm an over analyzer too.

Screaming Injun.....Since I will do snap rolls with my cub I beefed up the spar with 3/16 inch strips of yardstick so the spar cross section at the center 36 inches is an I-Beam. Less weight gets added that way. What is your weight and engine? I will use an OS 46FX and hope to keep it well below 8 pounds. My wing is all 4MM. I cut out the ailerons from the top and the bottom of the wing. This was complex since I had to build up the ailerons and also the hole in the wing left by cutting out the ailerons. I'm using four Robart rod type hinges on each aileron, inserting the rods into the wing top surface flutes. A coating of Permatex Silicone Adhesive/Sealant holds the rods inside the CORAPLAST flutes.

jamesg25.....The wing area is 5.12 square feet. The weight came in at 7 pounds wich surprised me. I have been up on three days with it. I forgot everything I ever knew about flying the J-3 Cub and have crashed it twice already. On the last crash if it had been balsa it would have been totaled ready for the garbage can. I'm still shifting weight to adjust the CG location. First flight was at 100 degrees F. and 95% humidity. The OS 46FX had no problem with it.

Please let us know exactly where your cg comes out to be. I made two corocubs per the plans and they both were so tail heavy I lost them. They were repairable but not looking new or "near new" any more. Pretty wrinkled up. I think I am going to try a "third" one soon but am concerned about cg. I made another spadet so I could have something else to fly again.
upnflyin

Remember that I'm using my own plans. Wing cord is 10-3/8, span is 71, CG is at 3-3/4 of chord. That works out to 36% of chord which is considered high. It flys great. I'm still test flying it so the CG may change. The incidences are zero and the engine down thrust is 2 degrees. Mine was very nose heavy. I moved the wing back 9/16 inch plus I moved components back. It is a floater. Looks like it glides all day. Making a decent landing has been difficult since it does not want to come down. I'm using an OS 46FX idling lower than I have ever idled one. Prop is 11 X5 APS. I may go to a 12 X 4 APS to see if it will slow the plane more. I have been landing on the mains and frequently nose over. The main gear is centered about 1/2 inch front of the wing LE so it should be doing better. Last few landings I flared more and this was a big improvement. I have not been flaring because I was afraid of a snap roll. I picked up an elevator flutter at high speed. I was using a piano wire bent into a C between the two elevator halves. It was .072 diameter. I just changed it to .093 diameter and would recomend something closer to .11 diameter. I also added some weight near the elevator TE in the form of three bamboo skewers to serve as dynamic vibration dampers. You say you lost two COROCUBS because they were tail heavy. Did you get them up in the air and around the field? You do know that a lot of right rudder is needed at takeoff. My first take off was a snap roll into the ground. I had forgotten all about the rudder.

thanks for the details.
I had no problems taxi or takeoff but as soon as it was up on its own it was super pitch sensitive. Tail heavy indications as far as I could tell. I made the circuit up and down a lot. A little down and it would dive and a little up would put it in a nose high stall condition. Higher airspeed made it even worse. The control deflections were not excessively large. Attempted landing and lost them. On the second one I made the nose longer and put a saito 80 on it for more weight. Better but not good enough.
I even broke out my incidence meter and checked everything including eng angles.
Think I will give it another go but make some minor changes.
upnflyin

Try aiming it at solid objects. The outhouse, a rock outcropping, big trees. I'm sure with enough effort and a little luck you'll be able to destroy that ugly cub so you can build an Aeronica like you should have started with anyways.